Oxygen Supply
How Do Astronauts Breathe in Space?
Most people can survive only a couple of minutes without oxygen, and low amounts of oxygen can cause fatigue and blackouts.
Most of the station's oxygen will come from a process called "electrolysis," which uses electricity from the ISS solar panels to split water into hydrogen gas and oxygen gas.
Why Is There No Oxygen In Space?
On Earth, gravity holds things to the Earth. For example, if you jump up, you come because gravity pulls you back. This is the same with gases like oxygen, they can't get very far from the Earth because gravity pulls them back.
On planets or moons that have very low gravity, gases can escape and enter space. But space is so big, that whatever gases are found in space, gases spread out so fast, that they are so far apart from each other that we say there is no gas in space. What we really mean is that there is so little gas in space that we can't use it to breath.
How Do They KeepThe Air "Clean"?
Keeping the air clean is a process that astronauts consider as it would take effect on their health. It is removed by using the Co2 processor which removes it. Then the access Co2 would then be vented into space.